SCID

SCID

• Types of primary immunodeficiencies
1. Antibody
2. Cellular, combined
3. Phagocyte
4. Complement
5. Malfunction of regulation
6. Syndromes with compromised DNA repair
Inheritance of immunodeficiency
1. X-linked recessive
  1. common in males more than females
What is SCID
1. Severe Combined Immunodeficiency
  1. highly susceptible to life-threatening infections
2. a rare condition
3. Caused by defects in any of several possible genes
  1. Adenosine deaminase deficiency
    1. ADA converts adenosine and deoxyadenosine to inosine and deoxyinosine
    2. Accumulation of dATP
      1. inhibition of ribonucleotide reductase
        B and T cells unable to divide
4. fatal, usually within the first year of life
5. Cellular and Humoral Components
  1. Cellular
    1. Thymus not present
      1. T cells will not mature
    2. Thymus present but T cells are not produced
      1. Thymus will shrink
  2. Humoral
    1. B cells affected from
      1. The absence of T cells
      2. cannot produce antibodies or cannot class switch
diagnosis of SCID
1. CBC + DBC
  1. Leukopenia if below 3000 in children younger than 1 year
2. Total serum immunoglobulin (Ig) levels
  1. IGM
3. Lymphocyte function
  1. Mitogenic signals
4. Chest x-ray
  1. thymus shadow
treatment and management of SCID
1. Protective management
  1. Isolated bubble
2. IV Ig
3. Prophylaxis
4. Stopping live vaccinations
5. Hematopoietic cell transplant
  1. First choice of treatment
6. Gene therapy
  1. Not available for everyone
  2. Very expensive
  3. Limited studies done on it reducing its reliability
7. Enzyme replacement therapy ERT
  1. Weekly IM
  2. Might require continuous Ig therapy
Role of MHC (MAJOR Histocompatibility Complex) , HLA (Human Leukocyte Antigen)
1. Histocompatibility
  1. Major Complex (MHC)
    1. Cluster of genes >>> Glycoproteins
    2. Discriminate self/ non-self
    3. Ag presenting structures
    4. Act as antigens in in-compatible recipient
  2. Minor Antigen (miHA)
    1. Cell-surface receptors of donated organs
    2. Polymorphic proteins e.g. H-Y/ HA-2
    3. A.A differences between donor & recipient
2. Classes of MHC Genes
  1. Class I
  2. Class II
  3. Class III
3. Features of MHC
  1. Highly Polymorphic
  2. Co-dominant Expression
  3. Low affinity, broad specificity
  4. Low affinity, broad specificity
Tests for Compatibility
1. Blood Typing
2. Tissue Typing
  1. Genomic typing: Allele specific PCR/Sequencing
3. Cross-Matching
  1. Complement-dependent Cytotoxicity
  2. Flow Cytometry
  3. Mixed Lymphocyte Culture
  4. Panel Reactive Antibody
4. Others
  1. ELISA
  2. Limiting Dilution Analysis
  3. Direct Cytotoxicity Assay
Donor guidelines
1. Medical suitability
2. Donor eligibility
3. Donor evaluation
4. pathogens that may be transmitted by the graft
5. Informed consent
6. Preoperative assessment
GVHD
1. Allograft
2. Definition
3. types
  1. acute GVHD
  2. Chronic GVHD
Post-transplant care recommendations
1. Long term screening
  1. Weekly visits for one month
  2. Biweekly visits in the next wo months
  3. Monthly visit for six two twelve months
  4. Vital signs, body weight and height in every visit
2. Vaccination
  1. vaccines should be offered from about 12 months post HSCT
  2. No live vaccines are given until at least 2 years post HCT
  3. Same as defaulters schedule
  4. patient’s surrounding family must be completely immunised
3. Screening for chronic GVHD
  1. allogeneic hematopoietic stem cell transplant should be monitored for chronic GVHD
Consent in organ donation
1. Informed consent
2. Required request
3. Presumed consent
Organ donation in Islam
1. living donor
  1. it is allowed to donate unless
    1. donor’s life is put at risk
      1. vital organs like the heart are not allowed to be donated
    2. physically cannot tolerate the operation
2. Dead donor

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	Created by Khaled Sadek almost 8 years ago